Automatic train control system



Aug. 6, 1935. A E, HUDD 2,010,720

AUTOMATIC TRAIN CONTROL SYSTEM Filed March 6, 1934' 3 Sheets-Sheet l 19 I 19 l I a? 1 1935; A. E. HUDD 2,010,720

AUTOMATIC TRAIN CONTROL SYSTEM Filed March 6, 19:54 s Shets-Sheet 2 INVENTOR Aug. 6, 1935 AUTOMATIC TRAIN CONTROL SYSTEM A. E. HUDD Filed March 6, 1934 3 Sheets-Sheet 3 INVENTOR Patented Aug. 6, i935 'I r I UNITED STATES PATENTQOFFICE Application March 6,1934, SerialNo. 714,259

In Great Britain August 16, 1932 24 Claims; 1(0'1. 24643) V This invention consists in improvements in or The shrouding'of the permanent magnet'may relating to automatic train control systems and be effected by 6. or more electr a to mechanisms constituting parts thereof. 1 ranged with a D P p d 3 Short Automatic train control systems are already tance from said permanent magnets. The ener- 5 'known in which a permanent magnet locatedvon gization of the shrouding means is controlled 5:

the train track is utilized to actuate a receiver through a track circuit similar to those comcarried on the train, whereby'av warning device monly used'by orin'conjunction with signal sysis energized and brakes are automatically applied terns, all of which is well known a d understood when the train approaches or is passing a signal by those'skilled. inthe art or itmay be effected set to other than a clear position. it 7 1 The track magnets are usually arranged to A further feature of the invention consists in extend across the track and each pole is'arranged that at each; operating location on the track,

to energize one only of a pair of collecting plates of there is disposed one or morevpermanent maga receiver on the train. This arrangement-has nets onone side of the centre line of the track by manually controlled circuits; l0

l5- necessitated employing a number of magnetsarand one or more permanent magnets arranged v ranged side by side in order to ensure the'requion the other side ,Of t e C e line and in that site time of operation of the receiver carried by two magnetically operated relays are provided ie train as it traverses the magnets; It has on said train on oppositesides of said centre been proposed to provide an upright horseshoe line- Pr f ra ly, Said relays a e so Operatively *permanent magnet on the track arrangedwith Co e ed to the b ake mecha ism that if one 20 its poles in the longitudinal direction of the track. relay O y i 'en the brake mechanism is Both of the poleswere arranged to operate directly P y applied; .W Q i both relays are energized upon a single armaturewhich was mounted in either simultane u ly- One Operating location, aswinging manner on the train. The movement i Succession after P i g two op ra in of the armature was arrangedlto actuate a'siga i n h br kem h n m i fully app nal device and the brake mechanism. The mag-' The Warning d v e S arranged o be d d net Was rendered inoperative by energizing cer-f when a relay. energized; tainwindings carried by the limbsthereof. e Atfult e featu of the'invention Consists in It has also been proposed to provide two sets that Y: D movable loaded of receivers on the train, one of which is enerh 8'- Spring gravity loaded) for p a gized by permanent magnets arranged with'their a warning device and/or brake mechanism, a depoles longitudinal along the track and the other tent for holdingsaid movable member in an enerreceiver being energized by electroemagnets an gized p s tioniand a movable armature Operated ranged. with their poles at right anglesxto those by the aforesaid track'magne t to release said-de- T of the permanent magnets. In such an arrangetent, and means for ing Sa d member to its 35 T ment, when both receivers were energized simul energized pos t In a arrangement in which taneously, the relay remained inoperative. 1 the'train brakes are operated pneumatically, said According to this invention, an automatic train movable loaded m m r islflmanged to p a control system comprises one orrmore permae an air control valve. 7 V a 40 nent magnets (e. g. bar magnetsbarranged In one constructiona form of the relay mech- 40 on the train track with their north and south anism the said movable loaded member. is formed poles in the longitudinal direction of the track; in two relatively movable p tbetween which is elcctro-magnet or mechanically operated shroudv disposed a compression spring for effecting the ing means associated with said permanent -mag-' 10ad .W P i engageable by Said nets and arranged to render said magnets-in detent andthe other of which controls (e. g. by

operative when the track is clear, a, receiver on the valve referred to above) the Warning device the train embodying a relay comprising two fixed and b a mechanism e e t resetting collecting plates spaced apart inthelongitudinal means is'soarranged that it requires to be given direction of the track so as to be successively a reciprocating movement, the movement in one so energized by both pole pieces of each magnet and directionbeing arranged to move the first said 5 having pole pieces spaced apart toprovide alflux part7 again into engagement-with the detent but leakage path; an armature arranged to bridge, which looks the other part, while the return said pole pieces, and mechanism operated by movement moves the second part into a position the movement of said armature to control "said for releasing the brakes and stopping the warnwarning device and/orsaid train brakes. ing device. p v r 55 The following is a description of a train control system according to this invention, reference being made to the accompanying drawings, in which- Figure 1 is a diagrammatic view of the general arrangement of the various parts of the system;

Figure 2 is a part side elevation and part section of a mounting for a track permanent magnet and electro-magnets for controllingthe leakage flux of the permanent magnets; V p I Figure 3 is a section on the line 3-3 of Figure 2; v 1 Figure 4 is a plan view of the arrangement shown in Figure 2; 3 r

Figure 5 is a part side elevation and part section of the relay mechanism carried by the train;

Figure 6 is a section on the line 66"0 f Figure 5;

Figure 7 is a plan view of the construction shown in Figure 6.

' Referring to Figure l, at each operating location on the'track, there are mounted two permanent magnets '50, one oneachside of the cen-' tre line of the track. The magnets are mounted on suitable supports II which are better seen inv Figures 2 to 4. The'upper faces of the magnets "are arranged to lie at a level of about one-inch above the tops of therails' l2 and the poles of the magnets'are arranged in the longitudinal di Shroudingt means, .not.

rection of the track.

shown in Figure lbut shdwn'in Figures Z'to 4, are mounted 'on the-magnet support for controlling the leakage flux of the" permanent magnet.

When the track is clear, the shrouding means are arranged to greatly minimize or eliminate the leakage flux. Mounted on the train are two magnetic relay'devices i3 one on'either side of the centre line of the train, only one of which is shown in Figure '1. -Each'r'elay device is con- I trolled by'two collecting plates 34, which are so disposed on thetr'ain as to be traversed "across the top iace'of amagnet from whichit is spaced about four inches. The relay device'is arranged to operate awarning whistle I5 and a valve which controlsthe flow of air through a pipe line IE to the brake mechanism; Hand-control mechanism H is provided for resetting therelay after it has been energized'by the track mechanism,

Turning to Figures 2 to 4, the shrouding means comprise two electro ma'gn'ets' 1 I8; the iron cores netic spacing members 2| so that the poles. of

the permanent magnets are 'separated from the cradles and poles 'ofthe electro-magnets. The electro-magnets are carried on soft iron yoke pieces zr which are secured to a base member 23 of non-magnetic cast iron, the permanent magnets and'the spacing members are retained within the-cradle 20, and the "cradle is secured in contactwith the-top of the electro-magnets by non-magnetic bolts 24. which extend through holes in'theyokemieces 22-andareprovided with nuts 24 at one end and wedge shapedheads 25 at the other end. With this construction, proand forrel'e'as'ing thebrakes whichhave' been vided the solenoids are not energized, it is found that the permanent magnets can be designed to aiiord a leakage flux which. will energize the relay as it passes over them. The path of this flux can, however, be controlled, and the leakage flux adequately reduced by energizing the solenoids so that insufficient leakage flux is afforded for energizing the relays.

In the construction described above, the permanent magnet is formed from an alloy of chromium steel and cobalt the latter being present in .the proportion of per cent. Convenient dimensions of the magnet are found to be twentyfour inches in length by 4. inches broad by 1 inch thick.

Turning now to the construction shown in Figures 5 to 7; there is shown a relay mechanism for controlling vacuum operated brakes. The train relay comprises two collector plates 3 3 of soft iron, which are arranged end to end lengthwise of the train and to one side of the centre line thereof. These collector plates are formed with upturned portions or brackets 35 (see Figure 6) which are provided with laterally facing pole pieces 36.

Asoft iron armature 3'! is arranged in front of the pole pieces and is secured by a spring blade 38 of phosphor bronze to a bracket 39 formed from non-magnetizable material, which bracketsthe collector plates are also connected; The armature is arranged to extend downwardly beneath the pole pieces and is pro vided with an outwardly turned lug it at its lower extremity. The lug is arranged to extend between the arms of two detent levers 41. The detent levers are mounted on horizontally disposed pivot pins 32 and are provided at their ends above the pivot pins with anti-friction rollers 43, while their lower extremities engage the aforesaid lugs 40.

The upper part of the bracket 39 is formed with a valve cavity i l and a valve guide G5. A plate valve 66 having a hollow stem fill is mounted in said valve guide and is arranged to engage a valve seat 48 disposed above it, which valve seat is'at the mouth of a part communicating with a warning whistle. The valve cavity below the valve communicates with a vacuum pipe 39 of-the'train'brake mechanism. Within the hollow stem of the valve is slidably mounted a vertically disposed rod 5l which is hollow at its upper part and is provided on its lower part with a shoulderl'il, and a shank 52 which extends between the aforesaid rollers '43. .Within the hollow'valve stern and hollow part of the member 58 is located a compression spring 53. When the relay isiset so that the train brakes are inoperative, the rollers d3 are retained in engagement with the shoulder 5! .by reason of the fact that theirv lower extremities are held apart by the lugs'MJ of the armature. The spring 53 forces thevalve 46 against its seating 43. As soon as the armature is energized by a permanent magnet on the track, the lugs ii? will be swung laterally out of contact with the detent levers, whereupon the spring 53 will force the shoulder 55 between the rollers 43 allowing the member 56 to drop to release the valve 65, whereupon the vacuum in the brake pipe line will be broken by'air entering through the warning whistle.

The mechanism for resetting the detent device and the valve comprises a vertically movable rod 54 mounted in bearings 55 in the bracket member 39; The upper end oft-he rod is connected by a steel cable 56 to a hand control (not shown).

The lowerend of the' rod'has secured to it a laterally extending abutment 61, the end of which is arranged beneath the shank 52 of the mem ber 50. Ahelical spring 51 surrounds the rod 54 and engages at one end with the abutment 61 and at the other end with a stop member 58 on the bracket39. Normally the abutment 61 is retained out of'engagement with the end of the shank member. A small bell crank lever 59 is mounted on said bracket member, one end of which is arranged to engage thehollow valve stem 41- and the other 'end of which may be brought into engagementwith the groove 8!] formed near theupper end of the rod 54. Thus, when the member 50 has been released by the detent levers, it may be reset by moving I the abutment 6'! upwardly against the action of the spring, whereby it is brought into contact with the shank 52 and forces the shoulder 5|- above the rollers v43. 1 The lower extremities of the detent levers arethen separated by a spring 6|,

permitting the *lug' 40 to spring back between them. Although this operation compresses the spring 53 within the valve stem, the valve cannotmove, since the end of the bell cranklever 59 is locked by being in contact with the main cylindrical surface: of the vertical rod 54. As soon as the rod is lowered, however, the end of the arm 59 can enter into the channel 50 whereupon the valve is permit'ted'to be moved. upwardly into contact withits' seat by said spring. The warning whistle then ceases and the brakes are released. i h

As already indicated above," the relay mechanism on the train maybe duplicated in which case the two valves are arrangedin parallel passages which botlrcommunicate with the main pipe line of the train. The sizeof the valves and valve parts are so selected that whenone is open the air flowing therethrough is only suflicient to apply the brakes partially while when both valves are open the flow of air *is sufiicient' to apply the way track with their north and southpoles in thelongitudinal direction of the track, means adapted to render said permanent magnetsinoperative when the track isclear, two'fixed magneticflux collecting plates onthe'train space'd'apart in the longitudinal direction of-the track and-so positioned as to be successively energized by" both poles of one of said permanent magnets when the train is in movement, a movable armature associated with said collecting: plates, a movable loaded member, a detent for holding said movableloaded member in. an energized position, which detent. is adapted tobe released by said armature and-signalling means connected to said -movable loaded member.

2. An automatic train control system comprising permanent magnets arranged on the railway track with their north andsouth poles in' the longitudinal direction of theutrack, means adapted to render said permanent. magnets inoperative when the track is clear, two fixed magnetic-fiux collecting plates on the train spaced apart in the longitudinal direction of the track.

and so positioned as to be successively energized byboth' poles of one of said permanent magnets when the train is in movement,'a movable armature associated witlrsaid collecting plates, a

movable loaded member, a detent for holding said movable loaded member in an energized po sition, which detent is adapted to be released by said armature and signalling and brake controlling means connected to the said movable loaded member.

3. An automatic train control system comprising permanent magnets arranged on the railway track with their north and south poles in the longitudinal direction of the track, means adapted torender said permanent magnets inoperative when the track is clear, two fixed magnetic-flux collecting plates on the train spaced apart in the longitudinal direction of the track and so positioned as to be successively energized by both polesof one of said permanent magnets when the train is in movement, a movable armature associated with said collecting plates, a movable loaded member,. a detent for holding said movable loaded member in an energized position, which detent is adapted to be released by said armature, signalling and brake controlling means connected to the said movable loaded member and hand-operated means for re-energizing said loaded member and effecting the reengagement of said detent therewith.

4. An automatic train control system compris-.

ing permanent magnets arranged on the railway track with their north and south poles in the longitudinal direction of the track, means adapted to render said permanent magnets inoperative when the track is clear, two fixed magnet-flux collecting plates on the train spaced apart in the longitudinal direction of the track and so positioned as to be successively energized by both poles of one of said permanent magnets when the train is "in movement, a movable armature associated with said collecting plates, a movable loaded member, a detent for holding said movable loaded member in an energized position, which detent is adapted to be released by said armature, pneumatic signalling and brake controlling mechanism, a valve for controlling said mechanism, which valve is connected to said movable loaded member.

5. An automatic train control system comprising permanent magnets arranged on the railway track with their north and south poles in the longitudinal direction of the track, means adapted to render said permanent 'magnets inoperative when the trackis clear,.two' fixed magnetic-flux collecting plates on the train spaced apart in the longitudinal direction of they track and so positioned as to be successively energized by both poles of one of said permanent magnets when the train is in movement, a movable armature associated with said collecting plates, two relatively movable members, signalling and brake contro'iling means connected to the first of said movable members, a compression spring disposed between said movable members, a detent for holding the second of said members in a position to energize said spring and force the first movable member into an inoperative position, which armature is adapt ed to release said detent whereby said signalling and brake controlling means are rendered operative. i

6. An automatic train control system comprising permanent magnets arranged on the railway track with their north and south poles in the longitudinal direction of the track, means adapted to render said permanent magnets inoperative when the track is clear, two fixed magnetic-flux collecting plates on the train spaced'apart in the longitudinal direction of the track and so positioned as to be successively energized by both poles of one of said permanent magnets when the train is in movement, a movable armature associated with said collecting plates, two relatively movable members, signalling and brake controlling roeans connected to one of said movable members, a compression spring disposed between said movable members, a detent for holding one of said members in a position to energize said spring and force the other member into an inoperative position, which armature is adapted to release said detent whereby said signalling and brake controlling means are rendered operative,

and reciprocable re-setting means adapted to engage both said members so that the movement of the re-setting means in one direction re engages one member with the detent but locks the other member in the position in which the signalling and brake mechanism are operative, while return movement of said re-setting means moves said latter member to render the signalling and brake mechanism inoperative.

7 An automatic train control system comprising permanent magnets arranged on the railway track with their north and south poles in the longitudinal direction of the track, electro-magnetic means adapted to render said permanent magnet '1 inoperative when the track is clear, two

magnetic-flux collecting plates on the train spaced apart in the longitudinal direction or the track and so positioned as to be successively energized by both poles or the permanent magnets when the train is in movement, pole pieces fixed to said collecting plates to provide a flux leakage between them, each of which pole pieces is provided with a face lying in an upright plane extending along the track, an armature mounted to I move towards and away from said pole pieces across the track, a movable loaded member, a detent for holding said movable loaded member in an energized position which detent is adapted to be released by said armature, and signalling and brake controlling means connected to said movable loaded member.

8. An automatic train controlisystemcomprising permanent magnets arranged on the railroad track with their north and south poles the longitudinal direction of the track, electromagnets arranged with their poles opposite the poles of the permanent magnets, means for energizing said electromagnets to be of opposite polarity to the permanent magnets, two fixed magnetic-flux collecting plates on the train spaced apart in the longitudinal direction of the track and so positioned as to be successively traversed by both poles of one of said permanent magnets and by the associated electromagnets when the train is in movement, a movable armature associated with said collecting plates, and signalling means on the train adapted to be controlled by said armature.

9. An automatic train control system comprising permanent magnets arranged on the railroad track with their north and south poles in the longitudinal direction of the track, electromagnets arranged with their poles opposite the poles of the permanent magnets, means for energizing said electromagnets to be of opposite polarity to the permanent magnets, two fixed magnetic-flux collecting plates on the train spaced apart in the longitudinal direction of the track and so positioned as to be successively traversed by both poles of one of said permanent magnets and by the associated electromagnets when the train is in movement, a movable armature associated with said collecting plates, and brake controlling means on the train adapted to be controlled. by said armature.

10. An automatic train control system comprising permanent magnets arranged on the railroad track with their north and. south poles in the longitudinal direction of the track,'electromagnets arranged with their poles opposite the poles of the permanent magnets, means for energizing said electromagnets to be of opposite polarity to the permanent magnets, two fixed magnetic-flux collecting plates on the train spaced apart in the longitudinal direction of the track and so positioned as to be successively traversed by both poles of one of said permanent magnets and by the associated electromagnets when thetrain is in movement, a movable armature associ ated with said collecting plates, and signalling and brake controlling means on the train adapted,

to be controlled by said armature.

11. An automatic train control system com-- prising permanent straight bar magnets arranged on the railroad track with their north and south poles in the longitudinal direction of the track,

two electro-magnets associated with each bar magnet, one opposite each pole, means for energizing said electromagnets to be of opposite po-V larity to the respective poles of the permanent magnets, twofixed magnetic-flux collecting plates on the train spaced apart in the longitudinal direction of the track and so positioned as to be successively traversed by both poles of one of said permanent magnets and by the associated electromagnets when the train is in movement, a movable armature associated with said collecting plates, and signaling means on the train adapted to be controlled by said armature.

12; An automatic, train control system comprising permanent straight bar magnets arranged on the railroad track with their north and south poles in the longitudinal direction of the track, an electro-magnet associated with each pole of each of the bar magnets, a pole of each of which electro-magnets comprises a cradle for a supporting the bar magnet, non-magnetic material adapted to space the bar magnet from said cradle, means for energizing said electromagnets to be of opposite polarity to the respective poles of the permanent magnets, two fixed magneticflux collecting plates on the train spaced apart in the longitudinal direction of the track and so positioned as to be successively traversed by both poles'of one of said permanent magnets and by the associated electromagnets when the train is in movement, a movable armature associated with said collecting plates, and signalling means on the train adapted to be controlled by said armature. I

13. An automatic train control system com-v prising permanent magnets arranged on the railroad track with their north and south poles in traversed by both poles-of onelofisaid permanent magnets and by the associated electromagnets when the train is-in moyement, pole piecesfixed to said collecting plates ,to provide a flux-leakage path, a movable armature. arranged in, one position to bridge said latter "pole pieces, and signalling and brake controlling means on thetrain controlled by the movement of said armature;

14. An automatic train control systemcomprising permanent bar magnets arranged 1 on both sides of an imaginary line extendingqalong the railroad track with their poles in ztheilongitudinal direction of the track, electromagnets arranged with their poles opposite the poles of the permanent magnets, means for energizing said electromagnets to beef opposite polarity to the permanent magnets, twopairs; ofmagnetic-flux collecting plates on the train, one pair on each side of said imaginary line, the plates of each of said pairs being spaced apart in the iongitudinaldirectionpofthe track and sopositioned as to be successively traversed, by bothpoles, of

one of said permanent magnets and bythe associated electromagnets, anarmature associated with each pair of plates, andbrakecontrolling ;means on the trainadaptedto be ,controlled by both of said armatures.

15; An automatic train control system comprising at each control location on the railroad track two long bar permanent magnets, one arranged on each side of the, center line'of the track with their poles in the longitudinal direction of the track, electromagnetsarrangedwith their poles opposite the poles, of the permanent magnets, means for energizing said electromagnets to be of opposite polarity to the permanent magnets, two fixed magnetic flux collecting plates on the train spaced apart in the longitudinal direction of 'the track and so positioned as to be successively traversed by both poles of one of said permanent magnets and by the associated electromagnets when the train is in movement, a movable armature associated with said collecting plates, and signalling means on the train adapted to be controlled by said armature.

16. An automatic train control system comprising at each control location on the railroad track two long bar magnets, one arranged on each side of the center line of the track with their poles in the longitudinal direction of the track, electromagnets arranged with their poles opposite the poles of the permanent magnets, means for energizing said electro-magnets to be of opposite polarity to the permanent magnets, two pairs of magnetic-flux collecting plates on the train, one pair on each side of said imaginary line, the plates of each of which pairs are spaced apart in the longitudinal direction of the track and so positioned as to be successively traversed by both poles of one of said bar magnets and by the associated electromagnets, an armature associated with each pair of plates, and brake controlling means on the train adapted to be controlled by both of said armatures.

17. An automatic train control system comprising permanent bar magnets arranged on both sides of an imaginary line extending along the track with their poles in the longitudinal direction of the track, electromagnets arranged with their poles opposite the poles of the permanent magnets, means for energizing said electromagnets to be of opposite polarity to thepermanent magnets, two pairs of magnetic-flux collecting plates on the train, one pair on each by thatwo armatures together. 319. Amautomatictrain control system comprisingipergnanent bar magnets arranged on both sidesof an imaginary lineextending along the track with their poles in the longitudinal direcadapted tome-controlled partly by either of said armatures alone or wholly by the two armatures "together.

l8. Anlautomaticltrain control system comprising permanent bar magnets arranged on both sides of; an; imaginary line extending along the track withtheirpoles in the longitudinal direc- ;tion,- of the -.tracl r,- electromagnets arranged with =their po1esopposite the poles of thepermanent ,magnets, means for energizing said electromagnetsto be of opposite polarity to the permanent magnets, two pairs of magnetic-flux collecting plates on the train, one pair on each side of said imaginary line, the plates of each of which pairs ,are spaced apart in the longitudinal direction .ofthe ltrack and sopositioned as to be successively traversed by both-polesl of one of said bar magnetsand by the associated electromagnets, an armatnre associated with each pair of plates, and signalling means on the train adapted to be controlled by either ofc-said armatures alone, and brakepontrolling means adapted to be controlled partly lby either of said armatures alone or wholly ,tion ofl,the track, electromagnets arranged with theinpoles opposite the poles of the permanent magnets, means for energizing said electromaggi o e ee p pq tero ar y 9 the e m t magnets, two pairs of magnetic-flux collecting plates on the train, one pair on each side of said imaginary line, the plates of each of which pairs are spaced apart in the longitudinal direction of the track and so positioned as to be successively traversed by both poles of one of said bar magnets and by the associated electromagnets, an armature associated with each pair of plates, and signalling and brake controlling means adapted to be controlled by both said armatures.

20. An automatic train control system comprising permanent magnets arranged on the railroad track with their north and south poles in the longitudinal direction of the track, electromagnets associated therewith, two fixed magnetic flux collecting plates on the train spaced apart in the longitudinal direction of the track and so positioned as to successively traverse both poles of one of said permanent magnets when the train is in movement, said electromagnets having their north and south poles opposite the south and north poles respectively of the permanent magnets, whereby the juxtaposed opposite poles of said permanent magnets and said electromagnets are simultaneously traversed by one of said collecting plates, a. movable armature associated with said collecting plate, and signalling means on the train controlled by said armature.

21. In an automatic train control system, permanent magnets on the railway track, means adapted to render said permanent magnets inoperative when the track is clear, magnetic-flux collecting plates on the train so positioned as to be energized by said permanent magnets when the train is in movement, a movable armature associated with said collecting plates, two relatively movable members mechanically loaded for movement relatively to one another, signal and brake control means connected to one of said movable members, a mechanical detent for holding said movably loaded member in an energized position, which armature is adapted to release said detent whereby said signal andbrake control means are rendered inoperative.

22. In an automatic train control system, permanent magnets on the railway track, means adapted to' render said permanent magnets inoperative when the track is clear, magnetic-flux collecting plates on the train so positioned as to be energized by said permanent magnets when the train is in movement, a movable armature associated with said collecting. plates, two relatively movable members, signalling and brake controlling means connected to the'first of said movable members, a compression spring disposed between said movable members, a detent for holding the second of said members in a position to energize said spring and 'force the first movable member into inoperative position, which armature is adapted to release said detent whereby said signalling and brake controlling mean are rendered operative.

23. An automatic train control system comprising permanent bar magnets arranged on both sides of an imaginaryline extending along the railroad track with their poles in the longitudinal direction of the track, electromagnets arranged with their poles opposite'the poles of the permanent magnets, means for-energizing said electro-magnets to be of opposite polarity to the permanent magnets, two pairs of magnetic-flux collecting plates on the train, one pair on each side of said imaginary line, the

plates of each of said pairs being spaced apart in the longitudinal direction of the track and so positioned as to successively traverse both poles of one of said permanent magnets and the associated electro-magnets when the train is in movement, a movable armature associated with each pair of collecting plates, signalling and brake controlling means, and means controlled by said armature for controlling said signalling and brake controlling means.

24, An automatic train control system comprising permanent bar magnets arranged on both'sides of an imaginary line extending along tne railroad track with their poles in the longitudinal direction of the track, electro-magnets arranged with their poles opposite the poles of the permanent magnets, means for energizing said electro-magnets to be of opposite polarity to the permanent magnets, two pairs of magneticflux collecting plates on the train, one pair on each side of said imaginary line, the plates of energize said spring and force the other member into an inoperative position, said armature being adapted to release its associated detent whereby said signalling and brake controlling means are rendered operative.

' ALFRED ERNEST HUDD. 

